In recent years there have been numerous advances in the level of understanding of how cancer cells grow inside a host. Generally, it is known that where a tumor or cancer becomes manifest, either there is a deficiency in the host""s immune system and/or the tumor cells secrete or express agents which block the normal response of the host""s immune system. In any event, there is a failure on the part of the host""s immune system to recognize the presence of the cancer cell as xe2x80x9cnon-selfxe2x80x9d. Because of this failure, the tumor cell and its progeny are allowed to grow without the benefit of predatory attack from the host""s immune system cells which are normally responsible for detection of abnormal conditions. Primarily, the immune cells responsible for such predatory attack are the white blood cells of the CD34 lineage including the lymphocyte-activated killer macrophages and the T8 killer cells. Cells derived from CD34 lineage naturally become differentiated to ten or more mature cell types dedicated to specific functions. The functionality is believed to be determined by factors, such as cytokines, leading to the next differentiated stage.
Although seemingly much is known of specific hematopoietic cells which have become differentiated into identifiable discrete cell types, little is known about the physiologic control mechanisms involved in such differentiation process. Thus, contemporary research has centered primarily on examination of specifically known cell types and the cell surface xe2x80x9cmarkersxe2x80x9d recognizable at each such differentiation stage. Conspicuously lacking in the art has been clearly useful information or understanding of physiological events taking place within the cells as they metamorphosized from one state to the next differentiated state.
Consistent with the current state of understanding such cell differentiation is the methodology utilized by leading physicians and researchers in treatment protocols for cancerous diseases. Over the past several decades, cancer treatment methodologies have centered on conventional therapies such as surgical excision, radiation, and the injection of potent chemical agents. Such methodologies have well recognized limitations and have, in many cases, been proved to cause much additional pain and suffering to the patient as well as unreliable long-term effectiveness.
Numerous recent treatments have attempted to affect tumor cells by direct manipulation of cells understood to be active in clearing the body of dead or improperly functioning cells. Understandably, the cells targeted for investigation have involved cells of the immune response system. However, recent attempts at blocking growth of tumor cells, though utilizing sophisticated methodologies (such as by attempting to block the immune suppression capacity of the tumor cells) have generally been unsuccessful. These attempts are still ongoing and are also of questionable benefit in bringing about reliable treatments resulting in long-term tumor remission.
Examples of methodologies in the recent art include targeted radiation and chemotherapy, injection of cytokines, injection of monoclonal antibodies to specific known tumor cell surface markers, and genetic therapies involving transforming cells with genes encoding factors believed to affect specific tumor states. One methodology has involved utilizing a class of natural immunostimulatory agents, particularly lymphokines, which are known to act as immunomodulators. Some lymphokines are produced by one T lymphocyte but act by signaling other T lymphocytes. Prior attempts have been disclosed in the art to regulate such immunomodulators by adding factors, such as Interleukin 2 (IL-2), to enhance or elicit an immune response to tumor cells and thereby trump the immunosuppression effect that many tumor cells exhibit. The difficulty with such past investigations directed at blocking immunosuppression is that they have either failed entirely or have only attacked specific antigenic markers produced by the tumor cells. Other methods of treatment have included direct injections of various cytokines. Still other methods have attempted stimulating the patient""s immune response cells using cytokines in the presence of the patient""s own cancer cells, then reinjecting the treated immune response cells. A number of attempts have been made along these lines and a significant percentage of the patients do not respond optimally to such interventions.
The results of treatments utilizing any of the above methods indicate that subpopulations of cancerous cells remain undetected and unaffected and are able to present later clinical manifestation of the cancerous state. For example, a number of very malignant cancers, such as glioblastoma multiforme, continue to be a death sentence prognosis for patients who are so afflicted. Virtually all patients relapse, even after conventional debulking, chemotherapy and radiation therapy. Typical survival after diagnosis is usually 18 months.
Other regiments include gene therapy. For example, when TGF-xcex2 detection gene is inserted into a host""s tumor cells in vitro, then injected to attempt to elicit an immune response, treatments are only temporarily successful and fail to provide a lasting benefit, even when combined with IL-2 co-stimulatory regimens. The temporary effect results because not all of the tumorous cells have been eliminated. This is because populations of tumor cells are heterogeneous in the variety of surface markers they present. Not all such markers will be available for presentation to cells responding to the protective response effects of TGF-xcex2 or IL-2. Thus, some cells are not properly recognized in the treatment regime and survive undetected.
There is therefore an ongoing need for a means of stimulating more effectively and completely the host""s immune response to serious disease and cancer states. The current invention has centered on the recognition that dendritic cells derived from precursor CD34+ and CD34xe2x88x92 stem cells may be specifically directed to become a programmable antigen presenting cells (pAPCs). The current invention shows that in fact the pAPCs may indeed be programmed to become programmed super antigen presenting cells (pSAPCs) having the capacity to elicit an immune response to any number of tumor antigen moieties after being xe2x80x9cloadedxe2x80x9d with either tumor derived RNA in toto or the poly A+ population thereof, or with the expressed proteins encoded by such RNAs including immune significant tumor antigens expressed therefrom.
It will be well appreciated in the hemopoietic cell art that dendritic cells are typically bone marrow-derived leukocytes which are known to play a central role in cellular immune responses. There are many aspects of dendritic cell ontogeny which remain poorly defined. However, most studies suggest that these dendritic cells emerge from the bone marrow, circulate in the peripheral blood in an immature form, and then enter tissues where they function as antigen-presenting cells or differentiate into macrophages. Once these dendritic cells capture a foreign body or some type of cell recognized as non-self, they then migrate to central lymphoid organs where they present these antigens to the T lymphocytes. Once the dendritic cell makes the presentation to the T lymphocytes, the T lymphocytes then mount an immune response.
Dendritic cells are difficult to study due to the scarcity of their populations and difficulty in growing these cells in cell culture. Dendritic cells can be derived from three readily available sources: (1) peripheral blood monocytes, (2) bone marrow and (3) umbilical cord blood. The functional differences between dendritic cells which are derived from the peripheral blood monocytes and those derived from bone marrow remain controversial. Dendritic cells possess ideal characteristics to be used as antigen-presenting cells. The key problems experienced by researchers has been both the inability to retrieve dendritic cells in sufficient quantity and to direct a stem cell to develop into a dendritic cell either in sufficient quantity or sufficient specificity. Therefore, if dendritic cells could be properly propagated and channeled, the fact dendritic cells possess ideal characteristics to generate a tumor-specific cellular immune response by processing and presenting tumor-associated antigens to primed CD4+ T lymphocytes, dendritic cells would offer a highly desirable and efficient means to initiate an immune response.
Moreover, the current state of the art in cancer research has focused on the science of recombinant DNA sequencing. In general, researchers are searching the genomes of cells for DNA sequences encoding genes responsible for causing either the cancerous state itself, or the cancer""s immunosuppressive effects. At least 6,000 genes have been identified and characterized. The human genome itself is estimated to harbor at least 100,000 genes. Additionally, it is believed that any given cell may express 20 to 45 thousand different genes during its life cycle, if not at one time. Cancer cells are believed to express numerous genes in addition to, or in lieu of, those normally expressed and in fact may express a greater number than the average normal cell.
Previously, researchers have focused on identifying various unique genes such as Her2neu or Brac-a, and have associated such specific genes with specific cancers. Unfortunately, by focusing on single genes so associated with a cancer, the possibility that such genes may have little significance with respect to an immunological response greatly increases. The reason that such single genes may not be all important to the cancer state and immune response is that such cancer cells are heterologous, not homologous, with respect to expression of surface antigen markers.
The present invention furthers the state of the art by making it clear that it is not significant to identify every single gene that is expressed on a cancer cells. Rather, that it is important to provide a means by which the expressed genes of a cancer cell may be presented along with, or in combination to, the immune response system by a means directly useful to the xe2x80x9cnaturalxe2x80x9d mechanisms of recognition utilized by immune system cells. The inventors of the present invention delineate how this may be accomplished by directed growth of dendritic cells to a state where they may become programmable antigen-presenting cells (pAPCs), capable of digesting a foreign cell (non-self), or ingesting foreign cell RNA in toto or as the poly A+ portion thereof, or the expression product encoded by such RNAs. The inventors intend for the pAPCs to select appropriate cancer RNA or RNA expression products to be most appropriate for presentation.
Although a similar digestion of nonself matter occurs in the natural setting with the aid of macrophages and other phagocytotic cells, the present invention avoids the conditions understood to occur in vivo and accomplishes enhanced digestion and presentation in vitro. The current invention provides for uniform conditions under which dendritic cells may be directed or evolved to a state where they may be highly effective in digesting and/or selecting appropriate cancer and other cell markers for presentation. The inventors hereby suggest that during the digestion process, the dendritic cell will itself identify those antigens of significance for the immune system meaning that it will select out some 10 to 20 or more antigens from a specific cancer cell, RNA, or RNA encoded product which have immunological significance. Under in vivo conditions of a host afflicted with a cancer, such selection may not be effectively recognized by the immune system, especially one that is compromised or masked. In contrast, under conditions of the current invention, the dendritic cell selected markers may be presented to T4 and T8 cells in an environment which will allow such T4 and T8 cells to become properly educated and activated so as to trigger a useful immune response.
The current invention provides a means by which the dendritic cell can be activated to become a xe2x80x9cprogrammablexe2x80x9d antigen-presenting cell or pAPC which is a xe2x80x9cmanufacturedxe2x80x9d dendritic cell line and which can further be xe2x80x9cimmortalizedxe2x80x9d. Immortalization of the pAPC allows for a suitable continuous source of cells which may comprise the basis of an allogenic vaccine. Therefore, the donor host or any host of the same allotype with the same disease, exhibiting such RNA in toto or poly A+ portion thereof, or the encoded protein therefrom, with this source of allogenic dendritic cells will create vaccines directed to particular tumors. Similarly, these allogenic dendritic cells may be mixed with representative samples of different tumors"" RNAs or RNA encoded products. For instance, the current invention contemplates combining a plurality of tumor""s RNAs and/or RNA expression products from progressive stages of the same cancer type. By representing differentiation periods in the disease state progression, a heterogeneous population of tumor cell antigens are presented to the pAPC and therefore a single vaccine may be created representing xe2x80x9cdifferent phasesxe2x80x9d of the cancer giving rise to a multivalent vaccine. Therefore, one vaccination using such an allogenic-based vaccine may protect against the whole spectrum of a specified cancer. Similarly, an allogenic vaccine for one very poorly differentiated cancer with many atypical features may also have an effect on more early stages of the same type of cancer or a different cancer, meaning that a vaccine made from allogenic pAPCs to glioblastoma tumor tissue, or its RNA, or its RNA expression products for instance, may prove efficacious in use with other unrelated tumors such as a prostate cancer. The current invention further provides for xe2x80x9ccommonalitiesxe2x80x9d between all cancers which makes possible a single allogenic vaccine that is effective for a multiple of different cancers. Thus, many features which are similar to all cancers may be provided for in a pSPAC for presentation to cells of the immune system, in effect providing immune-specific antigens with commonality between different tissue types.
The current invention also contemplates use in placing specific antigens on the pAPC which function in a regulatory surveillance mode to prevent recurrence of a new cancer or a heterozygous group of cancer cells from growing out of control. For example, a pAPC xe2x80x9cprogrammedxe2x80x9d for lung cancer may be used in effectively eliminating a host""s cancer using an xe2x80x9cautogenicxe2x80x9d lung cancer vaccine. Where a sub-group of cells survive this immune response, because a heterozygous group of antigens is not recognized as that presented by the pSAPC, a different pSAPC with xe2x80x9cmemoryxe2x80x9d to capture di novo cancers may also be used to educate immune system cells. Such pSAPCs equipped with xe2x80x9csurveillance antigensxe2x80x9d may be effective not only against a heterozygous group of tumor antigens but may also be used for surveillance in di novo cancers separate from the original cancer for which the host was treated using the autogenic vaccine.
It is therefore an object of the present invention to provide a method for stimulating a directed immune response in cells of a living organism. More specifically, it is an object of the invention to provide a means for stimulating immune response in cells of a mammal, and particularly of a human, by isolation, separation, and propagation of precursor DCs in high yield from the blood and marrow of patients afflicted with cancer. It is a further object of the invention that this means provide for predetermining the evolution of precursor cells into programmable antigen presenting cells suitable for presentation by mixing to preselected antigens to elicit a host immune response capable of recognizing any or all expressed markers of tumorous cells or any other xe2x80x9cnon-selfxe2x80x9d tumorous cells or RNA of said tumor cells, or expression products encoded by such RNAs, or other nonself antigens. The invention further contemplates a process for aiding treatment of both early and terminal stages of cancer and other infections and diseases.
A primary object of the invention is to provide a method of preventing, treating, reducing the severity, or possibly curing a disease in the subject by stimulating the subject""s immune response against the disease. The scope of the invention further contemplates providing treatment methodology for the whole spectrum of human diseases the successful treatments of which rely on stimulation of the immune system for fighting infections and cancerous states.
Another object of the invention is using pAPCs in treating solid tumors via a protocol wherein pSAPCs derived from pAPCs act as vaccines. Yet other specific objects of the invention include adding cancer cell RNA and RNA expression products directly into a pAPC whereby the protein antigens encoded by such RNA can be expressed on the surface of the pSAPC. Another embodiment of the invention contemplates extracting tumor RNA, cloning such RNA into bacterial expression vectors, then transforming the pAPCs with said vectors so that tumor gene products may be directly propagated in the pAPC for high level presentation by the pAPC to induce a specific immune response.
The invention further contemplates the creation of a vaccine to specific cancers including lung, prostrate, and breast cancers. Moreover, a preferred embodiment of the invention contemplates the creation of allovaccines which can be created by donor DCs adhering to the nine basic MHC-I and MHC-II phenotypes. Such allovaccines are further contemplated to include the immortalization of the nine DC lines known to derive from precursor CD 34 stem cells utilizing currently well characterized Epstein-Barr virus and other immortalization techniques (such as by retro and adenoviruses) understood by those skilled in the art. This embodiment contemplates that the immortalized allogenic DCs will be xe2x80x9cloadedxe2x80x9d with specific cancer cells, or RNA in toto or the poly A+ portion thereof, or gene products thereof, or bacterial expression vectors containing tumor cell genes derived from said RNA thereof, followed by mixing the treated DCs with a host""s plasmaphoresed T4 and/or T8 cells which mixture or resegregated cells (T4, T8, or pSAPC) would then be returned to the host""s system to induce the desired lasting immune response to the specified antigens and cancer cell markers.
The present invention provides for a method of extracting and separating precursor DCS from the blood of a mammal. A preferred embodiment contemplates extracting and separating a subject host presenting a diseased state the treatment of which requires host immunomodulation. The invention contemplates plasmaphoresing the blood to separate and isolate CD34+ and/or CD34-lineaged cells. In another preferred embodiment, bone marrow cells may be used in place of fresh whole blood. The isolated cells are then incubated with a specific regimen of treatments heretofore not appreciated in the art to create an antigen-presenting DC. The steps of creating the antigen-presenting DCs utilize an in vitro process to exclusively yield activated dendritic cells which can then be presented with a host""s disease state tumor cell or component parts or constructs thereof as previously described. The DCs thus activated are termed pSAPCs.
The invention contemplates generation of both autogenous pAPCs and allogenic pAPCs. Allogenic pAPC vaccines are created using the nine DC phenotypes based on the known histocompatibility complex antigens (MHC I and MHC II). Both autogenous and allogenic pAPCs may be xe2x80x9cprogrammedxe2x80x9d to any one or combination of such antigens. Programmed presenting cells (pSAPCs) are capable of eliciting xe2x80x9cupgradedxe2x80x9d cellular antitumor responses in the host""s T lymphocytes population via MHC class I and II pathways acting in association with accessory and adhesion molecules, such as B7-1, B7-2, and ICAM-1. The endocytic activities of these pathways are marked by a capacity to vigorously ingest fluid phase and whole cell lysates by macropinocytosis, and in turn deliver ingested solutes to prelysosomal MHC class II-rich vesicles for subsequent presentation as MHC class II surface molecules. The specific and channeled use of the DCs according to the present invention avoids the natural activity of the T lymphocyte""s response to a tumor cell which treatment regiments known in the art presently utilize. In such regiments, the T lymphocyte must locate the antigen directly from the host""s blood fluids or from the surface of the tumor itself. Thus, the T lymphocyte has only the chance to respond to antigens it can find, without the aid of highly activated programmed DCs, allowing for the tumor cell to evade immune surveillance either due to poor immunogenicity, or lack of the presence of a recognizable surface antigen. In contrast, the pAPC of the current invention are capable of xe2x80x9cdigestingxe2x80x9d a tumor, or its RNA, or expression products of such RNA, selecting suitable antigens so derived from the tumor, and expressing the antigens on the surface of the pAPC for presentation to other cells of the immune system either in vitro or in vivo.
A preferred embodiment of the invention contemplates utilizing the pAPCs as effective autogenic and allogenic vaccines and boosters against tumor antigens and cell markers in vitro or in vivo. Moreover, since the pAPCs have the capacity to become immortalized, the current invention contemplates creating banks of immortalized cells comprising activated pAPCs for use as allogenic vaccines and boosters.
The invention further contemplates mixing the pSAPCs with a host""s CD4+ T helper cells and CD8+ T killer cells which are isolated from whole blood or bone marrow. Such mixing under conditions of the present invention allows the antigens on the surface of the pSAPCs to be presented to the T cells, which presentation allows the T cells to become sensitized to the cancer-specific antigens. It is well-known in the art that such cancer-specific T lymphocytes are capable of mediating effective immune surveillance against subsequent manifestation of the specific cancer. Thus, once xe2x80x9cactivatedxe2x80x9d as described herein, the CD4+ T helpers and CD8+ T killer cells can be utilized as effective autogenic vaccines and boosters upon reinjection into the subject host, having been treated for activation according to the presently described and heretofore unrecognized method.
The mechanism of stimulation of the T cell is believed to occur according to the following description. First, naive CD4+ T cells when stimulated via presentation to the pAPC produced MHC class II antigens, become xe2x80x9ceducatedxe2x80x9d and initially produce IL-2. Next, they develop either into educated TH1 or educated Th2 cells, depending on the specific regiment utilized to produce the pAPC including the nature of cytokine regulation utilized, type of antigen presenting cell used, and the expression of accessory molecules of such cells. It is known that Th1 cells produce IFN-xcex3, TNF-xcex2 and IL-2, while Th2 cells are known to produce IL-4, IL-6, and IL-10. There are cross-regulatory effects between Th1 and Th2 cells mediated by the cytokines in the form of cross-cytokinic stimulation and inhibition. For instance, IL-4 inhibits the development of IFN-xcex3 producing cells while dysregulated IL-10 production normally serves to limit Th1 lymphocyte response.
The DC programming technique of the present invention uses the host""s dendritic cells derived from CD34+ and CD34xe2x88x92 cells to create programmable antigen-presenting DCs which are used in turn to stimulate activation of cytotoxic T-4 helper lymphocytes. The T-4 helpers in turn activate T-8 killer lymphocytes which attack tumor cells directly. The DCs ingest fluid phase-nonbinding antigens from whole cell lysates, or such cells"" RNA, or expression product of said RNA. The DCs may also be transformed with bacterial expression plasmids containing tumor cell cDNA. Once the DC has ingested said tumor antigens or has expressed tumor RNA, such antigens and expressed products are exocytosed after being processed by prelysomal MHC-I and MHC-II vesicles. From these prelysomal vesicles various antigens of the host""s tumor cells are transmitted to the surface of the now superpresenting pSAPC. The pSAPCs elicit effective antitumoral responses by presenting antigens to T-cell lymphocytes via MHC class I and MHC class II pathways as well as expressing necessary accessory and adhesion molecules such as ICAM-1, B7-1, and B7-2.
Another preferred embodiment of the invention contemplates taking advantage of the pAPC""s prolific expression of adhesion and accessory surface molecules and the responsiveness of T-lymphocytes to the pAPC presented antigens which responsiveness is overpowering compared to the previously evasive detection experienced by other immune stimulation protocols.
Yet another embodiment of the invention contemplates use of the successful activation and population expansion of tumor-specific T-4 and T-8 lymphocytes (utilizing phoresed lymphocytes in vitro) to provide a means of boosting old antergized T-cell populations.
As is understandable to those skilled in the art, the tumoral masking and successful camouflaging experienced in past treatment protocols due to anti-Th1 measures of contra-IL-10, IFN-gamma, and TGF-xcex2 are overcome by the pAPC of the present invention. Moreover, the present invention may also circumvent the temporary nature of enhanced solid tumor immunogenicity obtained in gene insertion/deletion therapies of IL-2/TGF-xcex2 caused by B7 and ICAM I or the interference from CD28/CTLA-4 and LFA-1, or effects of B7 on induction of INF-gamma. By co-incubation of pAPCs with the host""s tumor cells, with subsequent incubation with host T cells, the resulting antigens displayed and immunogenic response to be observed is profound.
The DC programming technique of the present invention further contemplates utilizing RNA from cancer cells that have already been excised from patients and either maintained in frozen preservation or preserved in paraffin cell blocks used for histology analysis. Thus, with this invention, one need only take surgical tumor specimens by invasive means on one occasion. The material preserved in paraffin blocks may be de-paraffinated by standard laboratory techniques and the messenger RNA from the tumor cells extracted. Whether from frozen stock or paraffin block, this RNA, which includes the cell""s mRNA, may then be used for direct incorporation into the dendritic cells or, may be used through standard in vitro expression methods to obtain encoded mRNA expression products for direct incorporation into the DC, or may be reverse transcribed into cDNA and cloned into bacterial expression vectors for transformation of the Dcs.